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TitleUnique features of the Cenozoic igneous rocks of Greece
 
AuthorPe-Piper, G; Piper, D J WORCID logo
SourcePostcollisional tectonics and magmatism in the Mediterranean region and Asia; by Dilek, Y (ed.); Pavlides, S (ed.); Geological Society of America, Special Paper 409, 2006 p. 259-282, https://doi.org/10.1130/2006.2409(14)
Image
Year2006
Alt SeriesEarth Sciences Sector, Contribution Series 20060576
PublisherGeological Society of America
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
AreaGreece
Lat/Long WENS 19.0000 28.0000 42.0000 34.0000
Subjectsgeneral geology; structural geology; tectonics; igneous and metamorphic petrology; igneous rocks; geodynamics; paleomagnetism; partial melting; earth thermal history; lithosphere; crustal evolution; magmas; fractional crystallization; faults, strike-slip; orogenesis; plutons; Cenozoic
Illustrationslocation maps; geochemical plots; cross-sections, structural; graphs; geological sketch maps; photographs
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
AbstractThe relationship between Cenozoic igneous rocks and the geodynamic evolution of the Aegean region is synthesized. A simplified palinspastic reconstruction of the region is attempted for the last 50 m.y., on the basis of published syntheses of paleomagnetic
data and estimates of amounts of extension and of shortening in nappes. Variability in magma genesis results from hydrous melting of the asthenospheric mantle wedge during subduction, thermal melting of enriched subcontinental lithospheric mantle as a result of rising asthenosphere, and decompression melting of rising asthenosphere. Break-off of a subducting slab or lithospheric delamination occurred
several times during the earlier Cenozoic as a result of Late Cretaceous and Paleogene closure of several Neo-Tethyan Ocean basins, triggering the rise of hot asthenosphere. Magmas underwent assimilation and fractional crystallization during passage through subcontinental lithosphere and crust; these processes were less effective where strike-slip faults provided efficient pathways for magma rise. Available data on the trace elements and radiogenic isotopes are used to identify the magmatic affinities of Cenozoic igneous rocks.
Unusual features of the Cenozoic igneous activity of the Aegean region are the wide range of rock types in "back-arc" settings and the exposure of both upper-crustal and middle-crustal rocks. This is a consequence of (1) the numerous microcontinental blocks within the Aegean area, separated by Neo-Tethyan Ocean strands that were destroyed by subduction; (2) orogen-parallel strike-slip faulting resulting from the progressive collision of Arabia with Anatolia; and (3) the extensional collapse and roll-back of the Hellenic subduction zone over subducting oceanic crust. Magmatism directly related to hydrous melting of subarc asthenosphere lay south of the present
south Aegean arc in the Paleogene; it influenced the Cyclades plutons in the Miocene and then moved southward again as a result of extension and roll-back to its present position. Calc-alkaline volcanism in Rhodope may be related to the subduction of the
Intra-Pontide Ocean. Lithospheric delamination or slab break-off produced thermal melting of the subcontinental lithospheric mantle inhomogeneously enriched by earlier subduction, resulting in voluminous shoshonitic volcanism in the Miocene of the northeast Aegean
and the Oligocene of Rhodope. In both cases, shoshonitic volcanism was followed by minor alkaline magmatism related to the decompression melting of upwelling asthenosphere. The thermal effects of upwelling asthenosphere, coupled with increased
geothermal gradient from extension, also contributed to the thermal melting of subcontinental lithospheric mantle. The plutonic rocks of the Cyclades and northern Greece resulted from crustal melting by magmas largely derived from the melting of lithospheric mantle.
GEOSCAN ID223330

 
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